Method and assembly for fracturing a borehole

ABSTRACT

A method for preparing a borehole for fracturing including inserting an assembly comprising a fracture plug, a setting tool, a perforating gun and a controller into a borehole, delivering the assembly to a target location, automatically recognizing the target location, automatically setting the plug of the assembly at the target location, and automatically initiating the gun of the assembly to perforate the borehole.

BACKGROUND

Fracturing of boreholes in the hydrocarbon recovery industry is a common activity. It will be recognized to those of skill in the art that fracturing plugs and setting tools are typically run to depth using electric wireline to set the plug where desired. A perforating gun may also be included with the plug and running tool to create holes in a borehole casing when desired. Currently at least one “round trip” (from surface depth to setting depth and back) of a wireline unit is always required per plug. While various methods currently available are effective, the cost of running strings in the borehole multiple times is significant and in some cases cost prohibitive to the anticipated productivity of a particular well comprising the subject borehole. The art is therefore always receptive to novel and useful innovations that reduce the need for wireline units or other means of conveyance.

SUMMARY

Disclosed is an embodiment of a method for preparing a borehole for fracturing including inserting an assembly comprising a fracture plug, a setting tool, a perforating gun and a controller into a borehole, delivering the assembly to a target location, automatically recognizing the target location, automatically setting the plug of the assembly at the target location, and automatically initiating the gun of the assembly to perforate the borehole.

Disclosed is an embodiment of a method for fracturing a borehole including inserting an assembly comprising a fracture plug, a setting tool, a perforating gun and a controller into a borehole, delivering the assembly to a target location, automatically recognizing the target location, automatically setting the plug of the assembly at the target location, automatically initiating the gun of the assembly to perforate the borehole, and pressuring on the borehole to fracture a formation surrounding the borehole.

Disclosed is an embodiment of fracturing assembly for a borehole including a fracturing plug, a setting tool operably connected to the fracturing plug, a perforating gun assembled in the assembly, a controller disposed in the assembly, the controller configured to sense location of the assembly and upon the assembly reaching a target location, the controller configured to autonomously cause setting of the fracturing plug and the firing of the gun.

BRIEF DESCRIPTION OF THE DRAWINGS

The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike:

FIG. 1 is a schematic view of an embodiment of a fracturing assembly in accordance with the present disclosure; and

FIG. 2 is a schematic view of another embodiment of a fracturing assembly in accordance with the present disclosure.

DETAILED DESCRIPTION

A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures.

Referring to FIG. 1, an assembly 10 for fracturing a borehole 12 in a subsurface formation 14 is illustrated. The assembly 10 is configured to be free of the need for a tether to the surface. More specifically, while prior art fracturing assemblies require a tether in the form of a string such as a wireline in order to position and operate the fracturing assembly of the prior art, the assembly 10 as described herein is configured to act and be autonomous. Consequently, no tether is needed. The assembly 10 includes a fracturing plug 16 (also referred to herein as “frac plug”) operably connected to a setting tool 18 that is enabled to set the frac plug 16 at a selected location in the borehole 12 or upon exposure to a selected set of circumstances or conditions. The assembly 10 further includes a perforating gun 20 (sometimes referred to herein as “perf gun” or “Guns”) connected to the frac plug 16 and setting tool 18 and finally a controller 22 that includes in embodiments, a battery, a sensor, and a processor for executing instructions upon criteria being met such as triggering the setting of the frac plug 16 and the initiating of the guns 20. It is to be understood that the frac plug, setting tool, and perf gun are all commercially available parts and therefore do not require specific enablement. Any frac plug, setting tool and perf gun tools may be selected and made up to create a part of the assembly disclosed herein. The controller comprises a microcontroller that is configurable as a programmer desires and in this case is configured to receive and send the signals discussed hereunder. The controller 22 may also be housed wherever is convenient in the structure of the frac plug, setting tool, and perf gun used herein. The controller is schematically illustrated at one end of the assembly 10 and may be in fact positioned there but also may be positioned in another convenient place on the assembly 10. Importantly, it is to be understood that previously used components that are tethered to surface and operated from surface are uniquely constructed according to this disclosure to have full autonomy thereby enabling an operator to simply drop the entire assembly into a borehole like a tripping ball and have the fracturing process be undertaken automatically until pressure is required at which point surface action will provide the needed fracturing pressure.

It is to be appreciated that the controller 22 may include any number of sensors that are configured to sense properties deemed useful in carrying out the intent of the assembly in a particular well. Sensors may be a casing collar locator, a gamma-ray detector, a hall effect (magnetic) sensor, Radio Frequency Identification (RFID) tag a chemical detection sensor, or even a mechanical profile sensor. For example, in embodiments the sensor may respond to one or more of a physical feature, an electromagnetic feature, a radiologic feature or a chemical feature whether the features be natural features of the formation, features of the borehole casing, tags placed in the casing, etc. Physical features include casing collars, a recess in the borehole, a profile extending radially inwardly of the borehole, etc. electromagnetic features include natural fields at the target location or a magnetic tag or RFID tag placed at the location prior to the deployment of the assembly. Radiologic features include natural signatures at the location, seismic signals (natural or induced), gamma ray signatures, etc. Chemical features may be signatures from chemical tags placed in the location prior to deploying the assembly. Finally, it is further contemplated that the assembly may include an accelerometer to gauge speed of the assembly 10 movement through the borehole 12. Regardless of the form of location acquisition, the assembly 10 is configured in one or more of these ways to find a particular place in the borehole 12 whereat the controller 22 signals the setting tool 18 to set the plug 16. All of this occurs without any intervention from or connection to the surface. Rather this all occurs autonomously within the assembly 10.

The frac plug 16 may be of a through-bore type or a no-through-bore type as desired. If a through-bore type frac plug 16 is employed, then the setting tool 18 will have a flapper or ball release-type configuration to close the frac plug 16 after setting so that pressure for fracturing the formation 14 can be built. Regardless of what type of frac plug 16 is made a part of the assembly 10, that plug is set by the setting tool 18 solely upon command from the controller 22 after the controller receives sufficient information from its sensor or sensors regarding whether or not the assembly 10 has achieved a target position within the borehole 12. Determination of sufficient information depends upon programming of the controller, which may be carried out in known ways of programming a controller. Upon the reception of the programmed requirements at the controller 22, the controller 22 sends a setting signal to the setting tool 18 to set the frac plug 16. After the frac plug 16 is set, the controller 22 following its set of instructions, will initiate the firing sequence for the guns 20, which may comprise one or more gun subassemblies. Firing of the guns is detectable at surface via acoustic wave reception (or by other methods) and fracture pressure is then applied to the borehole 12. Post fracturing, (single assembly 10 or post the operation of several assemblies 10), a mill is run to mill out the remaining structure and open the borehole 12.

In another embodiment, referring to FIG. 2, an additional function is added to the assembly. For clarity this assembly embodiment is denoted Assembly 30. Assembly 30, similar to assembly 10 includes a frac plug 36, a setting tool 38, a perf gun 40, and a controller 42. Assembly 30 also however comprises a braking system 44 having an arm 46 that is extensible or retractable relative to the system 44. In the extended position, the arm 46 may reduce flow area between the assembly 30 and the borehole 12 or the arm 46 may actually contact borehole 12. In either case, the deployment of arm 46 will cause progress of the assembly 30 to slow in the borehole, which may be important in deep wells for example where significant acceleration due to gravity can present an unattractive speed of the assembly 30. In embodiments where the system 44 is employed, the controller is programmed to sense a speed of the assembly 30 and deploy the arm 46 upon reaching a preselected threshold speed.

The embodiments discussed herein improve fracturing speed for a borehole and therefore reduce rig time and personnel required to bring a well to completion for as little cost as possible. In embodiments, a feature of the guns is that they are not capable of initiation until the assembly 10 or 30 has been inserted into the borehole. The feature is termed a “perforating gun interlock” for purposes of this disclosure. This prevents costly misfires requiring a redress of guns or replacement in order to achieve the fracturing necessary for the borehole. In an embodiment, the perforating gun interlock is a function of the controller 22, 42, which will not generate a fire command until at least two conditions are met. In an embodiment without a braking system 44, the controller 22 will not send a fire command to the guns unless the controller has already sent a setting signal to the setting tool 18, and a downhole condition has been verified, (such as pressure around the controller exceeding 200 PSI, for example). In an embodiment that includes a braking system 44, a third condition is added. Specifically, the controller 42 will not generate a fire command for the guns unless in addition to the foregoing conditions, the braking system 44 has been actuated as well. Once all three conditions are met, the controller will generate the fire command for the guns.

In use, the assembly 10 or 30 is inserted into a borehole generally at a surface location. Because the assembly 10 or 30 is specifically configured for nontethered activity in the borehole, the assembly 10, 30 may simply be dropped into the borehole and allowed to naturally fall to the target location. In the case of assembly 30, the braking system may be automatically deployed to slow descent if a preselected speed of descent is exceeded. Alternatively, and particularly if the borehole is deviated or horizontal, the assembly 10, 30 may also be pumped to the target location using any common wellbore fluid. Upon reaching the target location, determined through sensor readings as discussed above, the controller automatically will deploy the fracturing plug 16, 36 by triggering the setting tool 18, 38 to set the plug 16, 36. Subsequent to these activities, the controller 22, 42 will determine whether or not the conditions discussed above are present and if so, generate a fire command for the guns. Pressure may then be applied against the set plug to fracture the formation 14 through openings created by the perforating gun(s) 20.

Set forth below are some embodiments of the foregoing disclosure:

Embodiment 1: A method for preparing a borehole for fracturing including inserting an assembly comprising a fracture plug, a setting tool, a perforating gun and a controller into a borehole, delivering the assembly to a target location, automatically recognizing the target location, automatically setting the plug of the assembly at the target location, and automatically initiating the gun of the assembly to perforate the borehole.

Embodiment 2: The method as in any prior embodiment, wherein the delivering is dropping.

Embodiment 3: The method as in any prior embodiment, wherein the delivering includes pumping.

Embodiment 4: The method as in any prior embodiment, wherein the recognizing is by sensing one or more of a physical feature, an electromagnetic feature, a radiologic feature or a chemical feature.

Embodiment 5: The method as in any prior embodiment, wherein the physical feature is a casing collar, a recess or a profile

Embodiment 6: The method as in any prior embodiment, wherein the electromagnetic feature is a field.

Embodiment 7: The method as in any prior embodiment, wherein the electromagnetic feature is a Radio Frequency Identification (RFID) tag.

Embodiment 8: The method as in any prior embodiment, wherein the radiologic feature is a seismic signal or a gamma ray signature.

Embodiment 9: The method as in any prior embodiment, wherein the chemical feature is a chemical signature.

Embodiment 10: A method for fracturing a borehole including inserting an assembly comprising a fracture plug, a setting tool, a perforating gun and a controller into a borehole, delivering the assembly to a target location, automatically recognizing the target location, automatically setting the plug of the assembly at the target location, automatically initiating the gun of the assembly to perforate the borehole, and pressuring on the borehole to fracture a formation surrounding the borehole.

Embodiment 11: The method as in any prior embodiment, further comprising milling the assembly out of the borehole.

Embodiment 12: A fracturing assembly for a borehole comprising a fracturing plug, a setting tool operably connected to the fracturing plug, a perforating gun assembled in the assembly, a controller disposed in the assembly, the controller configured to sense location of the assembly and upon the assembly reaching a target location, the controller configured to autonomously cause setting of the fracturing plug and the firing of the gun.

Embodiment 13: The assembly as in any prior embodiment, further including a physical feature sensor.

Embodiment 14: The assembly as in any prior embodiment, further including a electromagnetic feature sensor.

Embodiment 15: The assembly as in any prior embodiment, further including a radiologic feature sensor.

Embodiment 16: The assembly as in any prior embodiment, further including a chemical feature sensor.

Embodiment 17: The assembly as in any prior embodiment, further including a braking system.

Embodiment 18: The assembly as in any prior embodiment, wherein the braking system includes an extendable arm.

Embodiment 19: The assembly as in any prior embodiment, further including a perforating gun interlock.

Embodiment 20: A fracturing assembly for a borehole consisting of a fracturing plug, a setting tool operably connected to the fracturing plug, a perforating gun assembled in the assembly, a controller disposed in the assembly, the controller configured to sense location of the assembly and upon the assembly reaching a target location, the controller configured to autonomously cause setting of the fracturing plug and the firing of the gun.

Embodiment 21: A borehole system having a fracturing assembly as in any prior embodiment therein.

Embodiment 22: A borehole system having a fracturing assembly as in any prior embodiment therein.

The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Further, it should be noted that the terms “first,” “second,” and the like herein do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. The modifier “about” used in connection with a quantity is inclusive of the stated value and has the meaning dictated by the context (e.g., it includes the degree of error associated with measurement of the particular quantity).

The teachings of the present disclosure may be used in a variety of well operations. These operations may involve using one or more treatment agents to treat a formation, the fluids resident in a formation, a wellbore, and/or equipment in the wellbore, such as production tubing. The treatment agents may be in the form of liquids, gases, solids, semi-solids, and mixtures thereof. Illustrative treatment agents include, but are not limited to, fracturing fluids, acids, steam, water, brine, anti-corrosion agents, cement, permeability modifiers, drilling muds, emulsifiers, demulsifiers, tracers, flow improvers etc. Illustrative well operations include, but are not limited to, hydraulic fracturing, stimulation, tracer injection, cleaning, acidizing, steam injection, water flooding, cementing, etc.

While the invention has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the claims. Also, in the drawings and the description, there have been disclosed exemplary embodiments of the invention and, although specific terms may have been employed, they are unless otherwise stated used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention therefore not being so limited. 

What is claimed is:
 1. A method for preparing a borehole for fracturing comprising: inserting an assembly comprising a fracture plug, a setting tool, a perforating gun and a controller into a borehole; delivering the assembly to a target location; automatically recognizing the target location; automatically setting the plug of the assembly at the target location; and automatically initiating the gun of the assembly to perforate the borehole.
 2. The method as claimed in claim 1 wherein the delivering is dropping.
 3. The method as claimed in claim 1 wherein the delivering includes pumping.
 4. The method as claimed in claim 1 wherein the recognizing is by sensing one or more of a physical feature, an electromagnetic feature, a radiologic feature or a chemical feature.
 5. The method as claimed in claim 4 wherein the physical feature is a casing collar, a recess or a profile.
 6. The method as claimed in claim 4 wherein the electromagnetic feature is a field.
 7. The method as claimed in claim 4 wherein the electromagnetic feature is a Radio Frequency Identification (RFID) tag.
 8. The method as claimed in claim 4 wherein the radiologic feature is a seismic signal or a gamma ray signature.
 9. The method as claimed in claim 4 wherein the chemical feature is a chemical signature.
 10. A method for fracturing a borehole comprising: inserting an assembly comprising a fracture plug, a setting tool, a perforating gun and a controller into a borehole; delivering the assembly to a target location; automatically recognizing the target location; automatically setting the plug of the assembly at the target location; automatically initiating the gun of the assembly to perforate the borehole; and pressuring on the borehole to fracture a formation surrounding the borehole.
 11. The method as claimed in claim 10 further comprising milling the assembly out of the borehole.
 12. A fracturing assembly for a borehole comprising: a fracturing plug; a setting tool operably connected to the fracturing plug; a perforating gun assembled in the assembly; a controller disposed in the assembly, the controller configured to sense location of the assembly and upon the assembly reaching a target location, the controller configured to autonomously cause setting of the fracturing plug and the firing of the gun.
 13. The assembly as claimed in claim 12 further including a physical feature sensor.
 14. The assembly as claimed in claim 12 further including a electromagnetic feature sensor.
 15. The assembly as claimed in claim 12 further including a radiologic feature sensor.
 16. The assembly as claimed in claim 12 further including a chemical feature sensor.
 17. The assembly as claimed in claim 12 further including a braking system.
 18. The assembly as claimed in claim 17 wherein the braking system includes an extendable arm.
 19. The assembly as claimed in claim 12 further including a perforating gun interlock.
 20. A fracturing assembly for a borehole consisting of: a fracturing plug; a setting tool operably connected to the fracturing plug; a perforating gun assembled in the assembly; a controller disposed in the assembly, the controller configured to sense location of the assembly and upon the assembly reaching a target location, the controller configured to autonomously cause setting of the fracturing plug and the firing of the gun.
 21. A borehole system having a fracturing assembly as claimed in claim 12 therein.
 22. A borehole system having a fracturing assembly as claimed in claim 20 therein. 